Method and device for regulating of the speed of a vehicle

ABSTRACT

In a method and a device for regulating the speed of a vehicle including an object detection system in the sense of an adaptive distance and speed control system, the adaptive distance and speed control system includes at least two operating modes. In the first operating mode, a vehicle speed between standstill and a limiting speed is set, and in the second operating mode, a vehicle speed between a limiting speed and a maximally regulable speed is set. In the first operating mode, in the absence of a speed-limiting object, the vehicle speed is increased beyond the limiting speed and thereafter is set to the limiting speed.

FIELD OF THE INVENTION

The present invention relates to a method and a device for regulatingthe speed of a vehicle having an object detection system, e.g., in thesense of an adaptive distance and speed control system having at leasttwo operating modes. In the first operating mode, a vehicle speedbetween standstill and a limiting speed is set, and in the secondoperating mode a vehicle speed between a limiting speed and a maximumregulable speed is set. In the absence of a speed-limiting object in thefirst operating mode, the vehicle speed is increased beyond the limitingspeed and is then set to the limiting speed.

BACKGROUND INFORMATION

An adaptive distance and speed control system is described in thepublication “Adaptive Cruise Control System—Aspects and DevelopmentTrends,” SAE paper 961010 published at the SAE International Congressand Exposition, Detroit, Feb. 26-29, 1996. In this system, radar wavesare emitted and partial waves reflected by objects are received. Therelative position, relative speed, and distance of objects from the hostvehicle are determined from the received signals and a power-determiningfinal control element of an internal combustion engine and/or thedeceleration devices of the vehicle are triggered as a function of thesedeterminations. If the radar sensor does not detect a lead vehicle, thehost vehicle is accelerated to a set intended speed and kept at thatspeed. If the radar sensor detects lead vehicles, the system switchesfrom the speed control described above to distance regulation and thehost vehicle follows the lead vehicle at a constant distance at the samespeed as the lead vehicle.

German Published Patent Application No. 199 58 520 describes a speedcontrol system for a motor vehicle which regulates the driving speed ofthe vehicle not only above a certain minimum speed but also at speedsbelow a predetermined limiting speed down to vehicle standstill.Automatic moving of the vehicle may be accomplished by detection of thetraffic situation by a distance sensor if the driver has responded to acorresponding moving message. The moving message is effective for apredetermined limiting time, but it may also be repeated as analternative. However, in any traffic situation, the driver has theopportunity to override the speed control by operating the acceleratorpedal or the brake pedal.

SUMMARY

An example embodiment of the present invention may provide a method anda device arranged in the sense of an adaptive distance and speed controlsystem for regulating the speed of a vehicle having an object detectionsystem. The adaptive distance and speed control system has at least twooperating modes, the vehicle speed being settable between standstill anda limiting speed in a first operating mode. This operating mode may alsobe referred to as low-speed following ACC (LSF-ACC) because thisoperating mode is arranged for congested traffic in which the vehicle ismoving only at low speeds and must stop frequently behind a lead vehicleand then begin moving again. This LSF-ACC operating mode is thus capableof automatically stopping and moving the vehicle, but the moving-off mayrequire confirmation by the driver. In addition, this low-speedfollowing assistant is arranged not to exceed a limiting speed. Thislimiting speed is in the range of 30 km/h, which also corresponds to thelower limiting speed of the second operating mode, for example. In thesecond operating mode, a vehicle speed is settable between a limitingspeed and a maximum regulable speed. This second mode correspondssubstantially to an adaptive distance and speed control system, asdescribed in the article “Adaptive Cruise Control System—Aspects andDevelopment Trends.” In this operating mode, the speed is set between aminimum adjustable speed, which may be the maximum regulable speed ofthe first operating mode, for example, and an adjustable maximum speedwhich may be in the range of 160 km/h to 180 km/h, for example. If thevehicle is accelerated up to the first speed in the first operating modeand if the road in front of the vehicle is clear, so that higher speedsmay also be set by the vehicle, the driver may be instructed to switchthe speed control system from the first operating mode to the secondoperating mode. This is possible by a visual or acoustic display, forexample, but it also may require the driver's attention and maynegatively impact driving comfort, because it may be impossible toascertain conclusively why the acoustic signal was triggered. Therefore,an example embodiment of the present invention may provide a method anda device which will instruct the driver intuitively, i.e., without anyinterfering and distracting acoustic and/or visual instructions, toswitch from the first operating mode to the second operating mode.

The vehicle speed may be continuously regulable above limiting speed v₀only after the driver has operated an operating element which switchesthe adaptive distance and speed control system from first operating modeA to second operating mode B.

In first operating mode A, it may be possible to implement a low-speedfollowing mode in which the vehicle may be automatically stopped andmoved again.

The driver may be informed visually and/or acoustically when thelimiting speed has been set.

At least one driver-operable device may be provided so that, when thisdevice is operated, first operating mode A switches to second operatingmode B.

Implementation of the method according to an example embodiment of thepresent invention in the form of a control element which is provided fora control unit of an adaptive distance and speed control system of amotor vehicle may be provided. A program capable of being executed on acomputer, e.g., a microprocessor or signal processor, and suitable forexecuting the method is stored in the control element. In this case, anexample embodiment of the present invention is implemented by a programstored in the control element, so this control element, provided withthe program, represents an example embodiment of the present inventionin a similar manner as the method for whose implementation the programis suitable. An electric memory medium may be used, e.g., as the controlelement, e.g., a read-only memory.

Additional features, possible applications, and aspects hereof are setforth in the following description of exemplary embodiments of thepresent invention which are illustrated in the Figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the speed ranges in which operating modes A and B areactive.

FIG. 2 illustrates a state transition diagram between operating modes Aand B.

FIG. 3 illustrates a v-t diagram of the method according to an exampleembodiment of the present invention.

FIG. 4 illustrates a schematic block diagram of an exemplary embodimentof the device according to the present invention.

DETAILED DESCRIPTION

FIG. 1 illustrates which operating mode is activatable in which speedranges. Speed axis 1, the left end of which represents a speed of zero,is illustrated, with the speed increasing toward the right. In addition,limiting speed v₀ is also entered here as well as maximum regulablespeed v₁. Operating mode A, which may also be referred to as low-speedfollowing control or LSF-ACC, is represented by hatched block 2. Thisoperating mode A is in effect at speeds between 0 and v₀, i.e., betweenstandstill and the limiting speed. In addition, second operating mode Bis also entered in the diagram, its speed range being represented byhatched range 3. This second operating mode, which includes the normaladaptive distance and speed control mode, is in effect at vehicle speedsabove limiting speed v₀, which is in the range of 30 km/h to 40 km/h,for example, and a maximum regulable speed v₁ of approximately 160 km/hto 190 km/h.

FIG. 2 illustrates a state transition diagram in which first operatingmode A is represented by first state 2 and second operating mode B isrepresented by second state 3. Transition 4 is executed to switch fromfirst operating mode A to second operating mode B. Transition 5 isimplemented to switch from second operating mode B to first operatingmode A. Transition 4, which switches the low-speed following assistantor LSF-ACC to a traditional adaptive distance and speed control mode,may be accomplished by a driver-operable operating element. Since thistransition 4 is associated with a higher vehicle speed and the driver isto retain control of the vehicle at all times, transition 4 may not beautomatic, but instead may occur only as a result of driver input.However, transition 5, which switches from traditional adaptive distanceand speed control mode to LSF-ACC, i.e., an LSF assistant, may occurautomatically because the driver recognizes the need for reducing speedand is able to implement this transition intuitively. Furthermore, it isalso possible for this transition 5 to occur automatically, because whenthe speed is below limiting speed v₀ in operating mode B, i.e., thetraditional adaptive distance and speed control mode, this may otherwisebe deactivated and the driver may be surprised as a result of theadaptive distance and speed control system shutting down. Since thetransition from operating mode A to operating mode B, i.e., from thelow-speed following assistant to the adaptive distance and speed controlmode, may be confirmed by the driver, it may be provided that the driverof the vehicle is notified that the road in front of the vehicle is freeand the lead vehicles are moving more rapidly than the host vehicle orare even accelerating, but the host vehicle is unable to acceleratefurther in operating mode A due to speed v₀ having been reached. Thismessage to the driver may be delivered such that it is intuitivelyunderstood by the driver and is not delivered by acoustic and/or visualsignaling devices (or not exclusively).

Other operating modes, e.g., deactivated speed control, are notillustrated in FIG. 2 for reasons of simplicity. It is thus possible todeactivate the speed control from operating mode A or operating mode Bat any point in time. When speed control is resumed, it is possible toactivate operating mode A or operating mode B from an inactive operatingmode, depending on whether the instantaneous vehicle speed is above orbelow limiting speed v₀.

FIG. 3 illustrates a v-t diagram illustrating a kinesthetic signalingoption, which notifies the driver that limiting speed v₀ has beenreached in operating mode A and that input by the driver is necessaryfor further acceleration of the vehicle. A time axis is plotted on theabscissa in the diagram in FIG. 3, beginning at any point in time t₀ atwhich the vehicle is at a standstill, for example as depicted in thedrawing. Vehicle speed v is plotted on ordinate 1. In addition, ahorizontal line 6 is plotted, showing limiting speed v₀ below whichoperating mode A is activatable and above which operating mode B isactivatable. There is a line 8 according to which the vehicle isaccelerated from a standstill at time t₀ and limiting speed v₀ isregulated asymptotically according to line 8. If the driver is notconcentrating fully on driving, he/she may not notice that limitingspeed v₀ has already been reached and that driver input is required toaccelerate the vehicle further. To signal to the driver kinestheticallythat driver input is required, the vehicle speed is controlled asindicated by line 9. Accordingly, the vehicle is accelerated from astandstill at point in time t₀ and the vehicle speed is increasedsignificantly above limiting speed v₀. However, object detection system13 with which the vehicle is equipped may not detect a lead vehicledriving more slowly or too near in front, limiting the speed of the hostvehicle. After the vehicle speed has been increased significantly abovelimiting speed v₀, the vehicle speed is lowered and regulatedasymptotically at limiting speed v₀. The driver of the vehicle thennotices that the vehicle is slowing down again, and if furtheracceleration is desired, driver input in the form of operation of anoperating element may be necessary. This overshooting according to line9 signals to the driver in a kinesthetic form and a comfortable mannerthat limiting speed v₀ has been reached, the road in front of thevehicle is free for further acceleration, and driver action is required.For example, if at time t₁, which is represented by line 7 in FIG. 3,the driver activates an operating element, triggering transition 4,which switches operating mode A to operating mode B, the vehicle is ableto accelerate further according to line 10 and may be operated furtherin an adaptive distance and speed control mode.

FIG. 4 illustrates a block diagram of the device according to an exampleembodiment of the present invention having an adaptive distance andspeed control device 11. This adaptive distance and speed control device11 has an input circuit 12 via which input signals may be sent to device11. For example, output signals of an object detection system 13 may beprovided as input signals. Object detection system 13 may be, forexample, a radar system or a lidar system which emits electromagneticradiation and receives reflected partial radiation, so that any leadvehicles are recognized and their relative positions, relative speeds,and distance from the host vehicle are determined. These variables maybe output by object detection device 13 to input circuit 12 via electricsignals. In addition, a driver-operable operating element 14 isprovided, for example, via which the driver signals to adaptive distanceand speed control device 11 that operating mode A is to be switched tooperating mode B and transition 4 is triggered. This driver-operableoperating element 14 may be, for example, a pushbutton on the steeringwheel, on the dashboard, on the central console of the vehicle, etc. Theoutput signal of this driver-operable operating element 14 is also sentto input circuit 12. Signals received by input circuit 12 are relayedvia a data exchange system 15 to a computation device 16. In computationdevice 16, actuator signals for deceleration devices 18 and apower-determining actuator of an internal combustion engine 19 arecalculated from the input data according to the operating mode active atthe moment. The output signals are transmitted via data exchange system15 to an output circuit 17 which the actuator signals for vehicledeceleration device 18 and a power-determining actuator of an internalcombustion engine 19, which may be, for example, an electricallycontrolled throttle valve or a device of a fuel injection pump whichinfluences the injection quantity. In addition, it is possible foroutput circuit 17 to trigger an acoustic and/or visual signaling devicewhich notifies the driver as to whether limiting speed v₀ has beenreached and whether driver operation is necessary.

1-6. (canceled)
 7. A method for regulating a speed of a vehicle, thevehicle including an object detection system arranged as an adaptivedistance and speed control system having at least two operating modes, avehicle speed settable between a standstill and a limiting speed in afirst operating mode, the vehicle speed settable between the limitingspeed and a maximum regulable speed in a second operating mode,comprising: increasing the vehicle speed in the first operating modebeyond the limiting speed in accordance with an absence of aspeed-limiting object; and after the increasing step, setting thevehicle speed to the limiting speed.
 8. The method according to claim 7,further comprising switching the adaptive distance and speed controlsystem from the first operating mode to the second operating mode byoperation of an operating element by a driver, the vehicle speedcontinuously regulable above the limiting speed only after operation ofthe operating element.
 9. The method according to claim 7, furthercomprising implementing a low-speed following mode in the firstoperating mode, the vehicle automatically stoppable and movable in thelow-speed following mode.
 10. The method according to claim 7, furthercomprising informing a driver at least one of (a) visually and (b)acoustically of the setting of the limiting speed.
 11. A device forregulating a speed of a vehicle, comprising: a detection deviceconfigured to detect objects in front of the vehicle; and an adaptivedistance and speed control system including at least two operatingmodes, the adaptive distance and speed control system configured to seta vehicle speed between a standstill and a limiting speed in a firstoperating mode and to set the vehicle speed between the limiting speedand a maximum regulable speed in a second operating mode, the adaptivedistance and speed control system including a calculation deviceconfigured to determine a vehicle speed to be set, the adaptive distanceand speed control system configured to increase the vehicle speed, inthe first operating mode and in accordance with an absence of aspeed-limiting object, beyond the limiting speed and to then set thevehicle speed to the limiting speed.
 12. The device according to claim11, further comprising at least one driver-operable device configured totrigger a switch from the first operating mode to the second operatingmode.